1. Field of the Invention
The present invention relates to a method and an apparatus for adjusting characteristics of an electron source equipped with many electron-emitting devices, and a method for manufacturing an electron source.
2. Related Background Art
Conventionally, two kinds of electron-emitting devices of a hot cathode device and a cold cathode device are known. As the cold cathode device of the two, for example, an electric field emission electron-emitting device (hereinafter referred to as an FE type), a metal/insulator-layer/metal electron-emitting device (hereinafter referred to as an MIM type), a surface conduction electron-emitting device (hereinafter referred to as a surface conduction emission device), and the like are known.
In an electron source in which many electron-emitting devices are wired in a passive matrix, and an electron generation apparatus and an image display apparatus to which the electron source is applied, it is desirable that the characteristics of each electron-emitting device are equal to make it possible to unify the emission luminance of each pixel.
However, because dispersion is generated in the electron-emitting characteristics of each emission device constituting the electron source to a certain extent owing to variations of processes of manufacturing, the dispersion of the characteristics appears as the dispersion of the luminance of each pixel if a display apparatus is made by the use of the emission devices. As a measure to the dispersion, a method for making the characteristics uniform by the use of the memorization property of the electron-emitting characteristic of the electron-emitting device is known (Japanese Patent Application Laid-Open No. 10-228867 and No. 2000-243256, U.S. Pat. No. 6,231,412 and EP No. 0,803,892).
If the equalization process is incorporated into the manufacturing process of an electron source, there is the possibility of the generation of the dispersion of the adjustment state of the drive of each device or the possibility of the generation of the dispersion of the adjustment state of the drive of each electron source panel. Consequently, the establishment of a more versatile equalization process capable of coping with such adjustment dispersion, also, is desired. That is, it is preferable to be able to provide a manufacturing process capable of manufacturing similar electron sources having high equality for a similar manufacturing process time even if the memorization properties of the electron-emitting characteristics of electron-emitting devices constituting an electron source differ from each other in some degree, or if the memorization properties differ from each of a plurality of electron sources in some degree.
For example, each device has a characteristic (a characteristic change curve) of an electron-emitting device peculiar to each device as shown in FIG. 14. Consequently, on the basis of the relation between emission currents Ie peculiar to each device and adjustment voltages Vshift, the most suitable adjustment voltage for obtaining a target emission current Ie1 has conventionally been selected to apply the selected voltage on a device to be adjusted.
Consequently, if the characteristic of each device is quite different from each other, it is necessary to apply a characteristic change curve of an electron-emitting device to each of the devices, and to prepare voltage values for the number of devices.
Consequently, the adjustment method becomes complicated. And if an adjustment apparatus is made in accordance with the adjustment method, the apparatus becomes complicated in structure and high in cost. And further, in a manufacturing method of an electron source incorporating the adjustment method as a part of the processes thereof, the adjustment method is a primary factor of making the management of manufacturing processes complicated.
An object of the present invention is to provide a method and an apparatus for adjusting characteristics, and a method for manufacturing an electron source, the methods and the apparatus making the characteristics of a multi-electron source to be almost the same in a simple process by the use of properties peculiar to an electron-emitting device.
According to the findings of the present inventors, it was discovered that a change rate of an electron emission current when a characteristic shifting voltage pulse was applied was almost proportional to the number of pulses, or a logarithm of a voltage application time, if the voltage was constant. And it was ascertained that the adjustment of the characteristics of devices could be performed by applying the same characteristic change curve of an electron emission current to devices having different initial electron emission currents in some degree by the use of the above-mentioned characteristic.
The gist of the present invention is to provide a method or an apparatus for adjusting characteristics of an electron source having a plurality of electron-emitting devices, and a method for manufacturing the electron source, the method for adjusting the characteristics including the step of:
applying a pulse of a voltage for adjustment to an electron-emitting device to be adjusted one or more times according to a characteristic of the electron-emitting device;
wherein:
the voltage for adjustment is selected from a plurality of voltages having discrete values according to the characteristic of the electron-emitting device; and
a number of applying times of the pulse is determined according to the characteristic of the electron-emitting device and the selected voltage.